Pi digits (again) - an unbounded spigot program

[Albert Chan]

(12-12-2021 11:04 PM)Albert Chan Wrote:  PI = 4/(1+1/(3+2^2/(5+3^2/(7+4^2/(9+5^2/(11 ...

This keep integers *much* smaller ⇒ code run faster.
see ABC Programmer's Handbook, Pi example

Translated for HP71B

10 P=1 @ Q=3 @ A=4 @ B=1 @ A1=12 @ B1=4
20 P=P+Q @ Q=Q+2 @ A0=A @ B0=B @ A=A1 @ B=B1 @ A1=P*A0+Q*A1 @ B1=P*B0+Q*B1
30 D=A DIV B @ R=A1-D*B1 @ IF R<0 OR R>=B1 THEN 20
40 DISP D; @ A=10*(A-D*B) @ A1=10*R @ GOTO 30

>run
3 1 4 1 5 9 2 6 5 3 5 8 9 7 9 3 2 3 8 4 5 6 2 ...

12 decimals float give 20 good pi digits.